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Ammonia (NH 3) can be produced by synthesis of nitrogen and hydrogen in the Haber-Bosch process, where one of the challenges is the availability of a sustainable and economic hydrogen source. Natural gas is currently the main feedstock for NH 3 production and a more environmentally sustainable alternative could be the use of biomass-based synthesis gas. The main objective of this paper is to perform a techno-economical evaluation of the production of biomass-based NH 3 from the integration of a pressurized entrained flow biomass gasifier (PEBG) in a paper and pulp mill. The synthesis and ammonia production were modelled in Aspen Plus, while a process integration model based on Mixed Integer Linear Programming (MILP) of an existing pulp and paper mill in Sweden was used to analyse the effects on the overall energy system of the mill. The approach to the integration between the two models was an iterative procedure, the most important constraint being the conservation of the steam balance in the mill. The results showed that the overall system efficiency (calculated in terms of electricity equivalents) is increased by 10%-units compared to the original operation of the mill where also the operation of a non-integrated gasification plant for ammonia production is included. The integrated process configuration produces NH 3 to a cost of 458 €/t and requires a relative high selling marginal to be economically feasible.

The main objective has been to describe different cases of the methanol production from steel-work off gases (Coke oven gas and Basic oxygen furnace gas) and biomass based synthesis gas. The SSAB steel mill in the town of Luleå, Sweden has been used as a basis to analyze four different methanol production cases. The studied biomass gasification technology is based on a fluidized bed gasifier unit, where the production capacity is determined from case to case coupled to the heat production required to satisfy the local district heating demand. Critical factors are the integration of the gases with availability to the synthesis unit, to balance the steam system of the biorefinery and to meet the district heat demand of Luleå. For each case, the annual production potential of methanol, the overall production efficiencies and the effects on the total steel plant have been estimated.

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